Nasal septal abscesses are commonly caused by nasal trauma, infection, and nasal surgery. As delayed treatment of nasal septal abscesses can cause various complications, including saddle nose, a prompt diagnosis with the relevant intervention is important. However, the diagnosis of nasal septal abscesses is difficult when nasal pain occurs after cauterization because there have been no formal reports of nasal septal abscesses owing to cauterization for epistaxis. Here, the authors report the first case of a nasal septal abscess that developed after cauterization. A 48-year-old woman underwent radiofrequency cauterization as a treatment for epistaxis. She developed nasal pain 10 days following cauterization, and a computed tomography scan revealed a nasal septal abscess. Careful observation should be undertaken in patients who undergo cauterization of the nasal septum, especially in patients complaining of nasal pain.